1. Field of the Invention
This invention relates to an anti-icing apparatus for use with devices that must remain in a body of water during sustained periods of below-freezing temperatures. In a preferred embodiment, the anti-icing apparatus is deployed with an aerator located in a pond or other body of water subject to possible freezing conditions.
2. Description of Related Art
A variety of devices are used in ponds or other bodies of water. In-pond aerators are one example of such a device, and in-pond aerators have been used in a variety of contexts. The terms “in-pond aerator” are used herein to refer to any aerator positioned within a body of water, whether the body of water is technically a pond or other type of reservoir. Thus, an in-pond aerator is any type of aerator positioned in any body of water to aerator the water.
In-pond aerators are often used in aquaculture, for example, to oxygenate the water body in order to provide optimum conditions for the fish or other living organisms being produced. Without aeration, many small to mid-sized bodies of water become stagnant, with low dissolved oxygen levels, increasing amounts of sludge build-up, and other related problems. These poor conditions can lead to a variety of problems, including fish kills, emissions of undesirable gases and odors, and an accumulation of sludge. Aerators of many kinds have been used to introduce oxygen into such bodies of water.
An improved aerator is disclosed and claimed in U.S. Pat. No. 8,016,273 to Dartez (the '273 patent). The '273 patent is hereby incorporated by reference, and the aerator design disclosed in the '273 patent is the starting point for a preferred embodiment of the present invention. That is, the present invention adds anti-icing structure to the improved aerator design disclosed in the '273 patent. This additional structure provides important benefits.
The aerator disclosed in the '273 patent does more than just oxygenate water. The improved aerator disclosed in the '273 patent creates flow within the body of water. It lifts water from the lower levels of the pond or other body of water, moves this water through the aerator housing, while infusing air into the water. This process not only aerates the water, it also turns over the water, effectively moving the lower water to the surface. In operation, the improved aerator of the '273 patent can turn over and circulate substantially all the water in a small to mid-sized pond or other body of water without the need for any additional equipment. Indeed, in most small to mid-sized bodies of water, the improved aerator disclosed in the '273 patent can accomplish this task without being moved around the water body. The aerator creates sufficient turnover and circulation that substantially all the water will be recirculated and oxygenated over time.
This combined turnover and aeration provide benefits in many contexts. Smaller bodies of water that might otherwise become stagnant, remain healthy and relatively free of sludge. Aquaculture ponds are oxygenated and the dissolved oxygen is distributed relatively uniformly throughout the pond. Sanitation and water recovery systems can use the improved aerator to make their operations more efficient.
To obtain these benefits, however, it is often necessary to operate the improved aerator during period of prolonged cold weather. When the temperature remains below the freezing point for substantial periods of time (e.g., for several days or more), the surface of small to mid-sized bodies of water will begin to freeze. A solid sheet of ice may form, or numerous large pieces of ice may form. When the temperatures remain low enough for long enough, several inches near the upper surface of the body of water will freeze.
Water expands as it freezes, and the expansion of an ice sheet on the surface of a body of water can exert great forces on objects within the water. This fact requires steps to prevent the formation of ice around such objects, to break up ice as it forms, or to remove the objects from the body of water before damage occurs. If an object must remain in the water for operational reasons (e.g., if an aerator is needed even during periods with sub-freezing temperatures), some means is needed to protect the object for damage that could result from the expanding ice sheet on the surface of the body of water.
It has been discovered that the improved aerator disclosed in the '273 patent generates sufficient turbulence in the water near the outlet side of the aerator to prevent the formation of ice in this region. The present invention incorporates certain components of the improved aerator and uses those components in a novel manner to prevent icing around the other three sides of the aerator. The aerator of the '273 patent has four sides, with one side being the outlet of the aerator. The three remaining sides have relatively large surface areas, typically covered by relatively thin, light-weight material (e.g., galvanized sheet metal or the like are commonly used). These structures are not built for strength and are, for that reason, particularly vulnerable to ice damage.
The remaining three sides of the aerator housing, however, remain largely unprotected. During normal operations, the water surrounding these three sides of the aerator housing is prone to icing when long periods of below-freezing temperatures occur. The water surrounding the three non-exit sides of the improved aerator does move, because the aerator tends to pull water in from these directions. But the majority of the water pulled into the aerator comes from below the aerator, thus leaving the surface of the water mostly undisturbed on the three non-exit sides of the housing.
Other devices also may be used in long-term, sub-freezing conditions. For examples, other types of aerators would be subject to similar forces if used in ponds or other bodies of water during prolonged periods of sub-freezing temperatures. Pumps, large valves, and other objects also may be used in such bodies of water during icing conditions. Water sampling or monitoring equipment and even barges, boats, and other watercraft are often subject to ice damage.
A means of protecting such objects from ice damage is needed. A low-cost, simple device is desirable. Because many aerators and other devices have electrical power, a device that runs on electricity would be particularly suitable for many applications. The present invention provides such a solution to these problems.